1. Field of the Invention
The present invention relates to a semiconductor device manufacturing method for controlling the film thickness or impurity concentration distribution with accuracy in a semiconductor device manufacturing apparatus in which oxide films are formed on semiconductor wafers and injected impurities are activated, thereby reducing variation in the production of semiconductor devices and improving the production yield.
2. Description of the Related Art
As semiconductor device design rules are further detailed, more accurate controls are required on thin films formed on semiconductor wafers and ultra shallow junctions (USJs) of doped impurities. Furthermore, as semiconductor wafers have larger diameter bores, controls are required for more uniform film formation and impurity concentration distribution over the wafer surface. For example, the insulating film at a gate electrode should be controlled with accuracy in the order of several nanometers over the wafer surface and between wafers. To this end, the semiconductor device manufacturing apparatus periodically processes data obtained from process monitors formed on a semiconductor wafer and measures the formed film thickness and impurity concentration distribution (generally substituted by the sheet resistance of the wafer surface), and analyzes the obtained data, thereby monitoring changes in the manufacturing apparatus condition.
However, as semiconductor devices are further down-sized, slight changes in the manufacturing apparatus condition affect the outcome of the manufacturing process in the manufacturing apparatus, making it difficult to realize a stable process by controlling only the manufacturing apparatus. For example, in an oxide film forming apparatus, even if wafers are controlled for the same temperature, actually formed oxide films are different in thickness depending on the condition of the film forming apparatus. In such a case, a process control (APC: Advanced Process Control) may be used for measuring the oxide film thickness of a process monitor and adjusting the processing time based on the film thickness to obtain a target film thickness.
For example, the Japanese Laid-Open Patent Publication No. 2007-59945 discloses an APC method wherein a process controller is provided in manufacturing apparatuses having a furnace used for thermal processing, such as low pressure CVD (chemical vapor deposition) apparatuses, and rapid thermal processors (RTPs). The controller calculates the oxide film thickness based on the gas flow rate and temperature obtained from the manufacturing apparatus and discontinues the process in the manufacturing apparatus when a desired film thickness is achieved.
On the other hand, the Japanese Laid-Open Patent Publication No. 2006-190795 discloses a method wherein the dimension of a gate electrode formed on a wafer is measured and the electric property of the semiconductor device over the waver is estimated based on the relationship between the gate length and electric property (gate threshold voltage, source-drain current, and the like). The processing temperature profile over the wafer surface is calculated based on the difference from the designed value and the relationship between temperature and electric property and compared with control data (temperature profile) of the manufacturing apparatus. Then, the temperature profile within the manufacturing apparatus is corrected to minimize variation in the electric property over the waver surface.